Distemper is a highly contagious disease caused by a
virus similar to the one that causes measles in people. Worldwide, it is the
leading cause of infectious disease deaths in dogs, although in the United
States it occurs only sporadically. All unvaccinated dogs are at high risk of
Infected animals shed canine distemper virus in all body secretions.
Inhaling the virus is the primary source of exposure. The highest incidence of
the disease occurs in unvaccinated puppies 6 to 12 weeks of age, at which time
maternal antibodies fall below protective levels.
Estrus, or heat, is the stage in a female dog's reproductive cycle during which she becomes receptive to mating with males. At this time, estrogen levels first increase and then sharply decrease, and mature eggs are released from the ovaries. Ideally, your dog should be spayed before she enters her first heat cycle.
Half the dogs who become infected with canine distemper virus show mild
signs of illness or no signs at all. The overall health of the dog has a lot to
do with how ill he becomes. The disease is most severe in dogs who are poorly
nourished and ill-kept.
The distemper virus tends to attack brain cells and cells that line the
surfaces of the body, including the skin, the conjunctiva, the
mucous membranes of the respiratory tract, and the gastrointestinal tract. The
disease takes a variety of forms. Secondary infections and complications are
common, partly attributable to the immunosuppressive effects of the virus.
The first signs of distemper appear six to nine days after exposure, and in
mild cases go unnoticed.
First stage is characterized by a fever spike of up to 103° to 105°F (39.4°
to 40.5°C). A second fever spike is accompanied by loss of appetite,
listlessness, and a watery discharge from the eyes and nose. These symptoms may
be mistaken for a cold.
During the next one to two weeks, very often the dog seems to be getting
better but then relapses. This often coincides with the end of the course of antibiotics and the development of gastrointestinal and
respiratory complications due to secondary bacterial invasion.
Second stage occurs two to three weeks after the onset of the disease. Many
dogs develop signs of brain involvement (encephalitis), characterized by brief
attacks of slobbering, head shaking, and chewing movements of the jaws (as if
the dog were chewing gum). Epileptic-like seizures may occur, in which
the dog runs in circles, falls over, and kicks all four feet wildly. After the
convulsive episode the dog appears to be confused, shies away from his owner,
wanders about aimlessly, and appears to be blind.
In cases with brain involvement in which the diagnosis is uncertain, a
spinal tap and analysis of cerebrospinal fluid may be of assistance. But this
is not always diagnostic. Another indication of brain involvement is distemper
myoclonus, a condition characterized by rhythmic contractions of muscle groups
at up to 60 contractions per minute. The jerking can affect all parts of the
body, but is most common in the head. Myoclonus is first seen when the dog is
resting or sleeping. Later it occurs both day and night. Pain accompanies
myoclonus, and the dog whines and cries. If the dog recovers, the jerking
continues indefinitely-but becomes less severe with time.